Use of Cell Switch Assistance Information for SSB Searching During Satellite Switching

Abstract

A UE, connected using a current cell served by a first satellite to a BS, receives information from the BS including assistance information for a cell switch from the current cell to a cell served by a second satellite. The information is received before a stop time indicating when the current cell will stop serving the UE. The UE performs the cell switch from the current cell to the cell served by the second satellite using at least the assistance information to find cell synchronization block(s) for the served by the second satellite. The BS sends the information from the BS including the assistance information for a cell switch from the current cell to a cell served by a second satellite. The BS shuts down the current cell at a stop time.

What is claimed is: 
     
         1 . A method, comprising:
 receiving, by a user equipment connected using a current cell served by a first satellite to a base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite, wherein the information is received before a stop time indicating when the current cell will stop serving the user equipment; and   performing, by the user equipment, the cell switch from the current cell to the cell served by the second satellite using at least the assistance information to find one or more cell synchronization blocks for the served by the second satellite.   
     
     
         2 . The method according to  claim 1 , wherein:
 the assistance information comprises one or more time offsets relative to existing cell timing for the current cell; and   performing the cell switch uses at least the one or more time offsets to find the one or more cell synchronization blocks for the cell served by the second satellite.   
     
     
         3 . The method according to  claim 1 , wherein:
 the assistance information comprises a frequency offset of one or more cell synchronization blocks to use for detection, measurement, and evaluation of the one or more cell synchronization blocks of the cell served by the second satellite; and   performing the cell switch uses at least the frequency offset to find the one or more cell synchronization blocks for the cell served by the second satellite.   
     
     
         4 . The method according to  claim 3 , wherein:
 the assistance information comprises an additional value of a frequency offset, wherein a first frequency offset is an offset to a first subcarrier of one or more cell synchronization blocks used by the current cell, and the additional value of the frequency offset is from the first frequency offset to a first subcarrier of the one or more cell synchronization blocks to use for synchronization for the cell served by the second satellite; and   performing the cell switch uses at least the first frequency offset and the additional value to find the one or more cell synchronization blocks for the synchronization for the cell served by the second satellite.   
     
     
         5 . The method according to  claim 1 , wherein:
 the assistance information comprises a different set of locations in time and frequency for the one or more cell synchronization blocks that is provided corresponding to the cell served by the second satellite, wherein the different set of locations is different from a set of locations in time and frequency for one or more cell synchronization blocks corresponding to the current cell; and   performing the cell switch uses at least the different set of locations to find the one or more cell synchronization blocks for the cell served by the second satellite.   
     
     
         6 . The method according to  claim 1 , wherein:
 the assistance information comprises a time interval for the user equipment to perform a search for a re-synchronization attempt to the cell served by the second satellite; and   performing the cell switch uses at least the time interval to find the one or more cell synchronization blocks for the cell served by the second satellite.   
     
     
         7 . The method according to  claim 1 , wherein:
 the assistance information comprises ephemeris information corresponding to the second satellite to apply when attempting a re-synchronization to the cell served by the second satellite; and   performing the cell switch uses at least the ephemeris information to find the one or more cell synchronization blocks for the cell served by the second satellite.   
     
     
         8 . An apparatus, comprising:
 one or more processors; and   one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to perform:   receiving, by a user equipment connected using a current cell served by a first satellite to a base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite, wherein the information is received before a stop time indicating when the current cell will stop serving the user equipment; and   performing, by the user equipment, the cell switch from the current cell to the cell served by the second satellite using at least the assistance information to find one or more cell synchronization blocks for the served by the second satellite.   
     
     
         9 . The apparatus according to  claim 8 , wherein:
 the assistance information comprises one or more time offsets relative to existing cell timing for the current cell; and   performing the cell switch uses at least the one or more time offsets to find the one or more cell synchronization blocks for the cell served by the second satellite.   
     
     
         10 . The apparatus according to  claim 8 , wherein:
 the assistance information comprises a frequency offset of one or more cell synchronization blocks to use for detection, measurement, and evaluation of the one or more cell synchronization blocks of the cell served by the second satellite; and   performing the cell switch uses at least the frequency offset to find the one or more cell synchronization blocks for the cell served by the second satellite.   
     
     
         11 . The apparatus according to  claim 10 , wherein:
 the assistance information comprises an additional value of a frequency offset, wherein a first frequency offset is an offset to a first subcarrier of one or more cell synchronization blocks used by the current cell, and the additional value of the frequency offset is from the first frequency offset to a first subcarrier of the one or more cell synchronization blocks to use for synchronization for the cell served by the second satellite; and   performing the cell switch uses at least the first frequency offset and the additional value to find the one or more cell synchronization blocks for the synchronization for the cell served by the second satellite.   
     
     
         12 . The apparatus according to  claim 8 , wherein:
 the assistance information comprises a different set of locations in time and frequency for the one or more cell synchronization blocks that is provided corresponding to the cell served by the second satellite, wherein the different set of locations is different from a set of locations in time and frequency for one or more cell synchronization blocks corresponding to the current cell; and   performing the cell switch uses at least the different set of locations to find the one or more cell synchronization blocks for the cell served by the second satellite.   
     
     
         13 . The apparatus according to  claim 8 , wherein:
 the assistance information comprises a time interval for the user equipment to perform a search for a re-synchronization attempt to the cell served by the second satellite; and   performing the cell switch uses at least the time interval to find the one or more cell synchronization blocks for the cell served by the second satellite.   
     
     
         14 . The apparatus according to  claim 8 , wherein:
 the assistance information comprises ephemeris information corresponding to the second satellite to apply when attempting a re-synchronization to the cell served by the second satellite; and   performing the cell switch uses at least the ephemeris information to find the one or more cell synchronization blocks for the cell served by the second satellite.   
     
     
         15 . An apparatus, comprising:
 one or more processors; and   one or more memories storing instructions that, when executed by the one or more processors, cause the apparatus to perform:   sending, by a base station to a user equipment connected using a current cell served by a first satellite to the base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite; and   shutting down, by the base station, the current cell at a current location at a stop time.   
     
     
         16 . The apparatus according to  claim 15 , wherein the apparatus is further caused to perform:
 before the shutting down, sending one or more cell synchronization blocks in the cell served by a second satellite according to the assistance information for the cell switch.   
     
     
         17 . The apparatus according to  claim 15 , wherein the apparatus is further caused to perform:
 before the shutting down, communicating with an other base station so the other base station sends one or more cell synchronization blocks according to the assistance information for the cell switch.   
     
     
         18 . The apparatus according to  claim 15 , wherein the cell switch uses one of a change in physical cell identification between the current cell and the cell served by the second satellite, or a same physical cell identification for both the current cell and the cell served by the second satellite. 
     
     
         19 . The apparatus according to  claim 15 , wherein the one or more cell synchronization blocks comprise corresponding one or more synchronization signal blocks comprising both search signals and physical broadcast channels. 
     
     
         20 . The apparatus according to  claim 15 , wherein both the current cell and the cell served by the second satellite cover a same geographical area. 
     
     
         21 . The apparatus according to  claim 15 , wherein the cell switch comprises a soft cell switch where there is overlapping satellite coverage at least at a switching time.